Methods are already known for obtaining a polygonal section box on a single manufacturing line by means of successive folding operations on a card blank, which operations are more particularly referred to as "wrap-around" operations.
For example, Document US-A-4 308 020 teaches one such technical method that enables a box to be made from a card blank by means of a suitable machine fitted with a mandrel, the box also containing the object to be packaged, such as a bottle in this case, and the blank being wound around said mandrel. To this end, the blank includes a sequence of four panels connected to one another via parallel fold lines, and provided with lateral flaps that are connected to respective ones of said panels via fold lines perpendicular to the fold lines of said panels. In that document, the mandrel is hollow so as to receive the bottle to be packaged, and it is square in section. The four panels are then rectangular and identical and they are wound around the mandrel by folding so as to form the four faces of the lateral belt of the box, after which the lateral flaps situated at one end of the panels are folded to form the bottom of the box, and then, after the mandrel has been removed from the lateral belt of the box while leaving the bottle therein, the lateral flaps situated at the other end of said panels, are in turn folded to constitute the cover of the box containing said bottle.
Although that wrap-around type method gives results that are satisfactory since it makes it possible at the end of the manufacturing line, to obtain a box or packaging containing the object concerned and made from a blank, it nevertheless suffers from a certain number of drawbacks.
Firstly, in order to make the box, it is necessary to have a plurality of distinct workstations along the manufacturing line in order to form the lateral belt thereof, its bottom, and its cover on the basis of the panels and flaps of said blank.
Further, it appears difficult to package a group of objects, particularly if they are cylindrical. The danger is that they will not be held sufficiently tangentially in the desired position firstly against one another and secondly against the faces of the box constituted by said panels, e.g. when the mandrel is being removed, and as a result they may strike one another or be damaged during subsequent operations and handling of the boxes.
Furthermore, disposing an object, often such as a circular section bottle, in a box that is square in section does not cause the bottle to be effectively immobilized since it is in tangential contact only with no more than four lateral faces of the box. The four corners of the box constituted by two adjacent lateral faces of the box and defining 90.degree. angles are empty, such that the bottle can move inside the box.
Also, the four corners of a square section box run the risk of being damaged since they project, and they do not impart any increased compression strength to the box. Furthermore, the four projecting corners of the box represent a significant loss of card blank material. In addition, from the point of view solely of appearance, making a box that is purely in the form of a right parallelepiped is very ordinary and not very attractive, commercially.